Objectives To provide rapid and practical techniques for collecting feces in the field, processing fecal steroids in the laboratory, and for monitoring reproductive function of free-ranging primates. New techniques have been developed for extracting steroids from the feces of primates. With a simple ethanol and water extraction, we are able to demonstrate 85% to 100% recoveries of fecal steroids from all the primates tested. The new technique was developed for extracting the feces in the wild and bringing only the steroids back to the laboratory for analysis. This reduces 1) the possible spread of infectious agents entering the US, 2) the time of laboratory analysis, and 3) the size of samples to be transported. The extraction technique is easy to accomplish, requires limited equipment in the field and the reagents can be purchased in primate countries. The extraction technique has been used on feces from the muriqui, the patas monkey, common marmosets, capuchin monkeys and cotton-top tamarins. For the muriqui, the new extraction technique plus direct, non-column RIAs have been validated and correlated well with our previous technique (r=0.81, p<.01). Daily and near daily fecal collections from five wild female muriquis were analyzed for estradiol and progesterone concentrations. Muriqui ovarian cycle lengths were found to be an average of 20 days and gestational length was around 218 days. The females cycled many times during the breeding season prior to conception. Early onset of cycling during the breeding season was not associated with an early conception and pregnancy. Additional samples collected from the only two breeding captive muriqui females from the Rio de Janeiro Primate Center, both urine and feces, were analyzed to determine the profiles of urine and fecal steroids to the urinary LH peak. Furthermore, HPLC separation and identification of testosterone and cortisol from muriqui and cebus feces and cortisol from female common marmosets were conducted and validated with testosterone and cortisol ELISAs to provide preliminary information for future studies. Keywords technique development, fecal steroids, urine hormones, ovulation, pregnancy